1. Technical Field
A free standing film containing nanotubes is prepared by the process described herein. Depending on the type of nanotubes, the free standing film is useful as an optical filter, as an anisotropically electrically conductive film (ACF), or as a thermal interface material (TIM).
2. Problems to be Solved
Electronic components such as semiconductors, transistors, integrated circuits (ICs), discrete devices, and others known in the art are designed to operate at a normal operating temperature or within a normal operating temperature range. However, the operation of an electronic component generates heat. If sufficient heat is not removed, the electronic component will operate at a temperature significantly above its normal operating temperature. Excessive temperatures can adversely affect performance of the electronic component and operation of the device associated therewith and negatively impact mean time between failures.
To avoid these problems, heat can be removed by thermal conduction from the electronic component to a thermal management aid such as a heat sink. The heat sink can then be cooled by any convenient means such as convection or radiation techniques. During thermal conduction, heat can be transferred from the electronic component to the heat sink by surface contact between the electronic component and the heat sink or by contact of the electronic component and heat sink with a TIM. The lower the thermal impedance of the TIM, the greater the flow of heat from the electronic component to the heat sink.
Surfaces of the electronic component and the heat sink are typically not completely smooth; therefore, it is difficult to achieve full contact between the surfaces. Air spaces, which are poor thermal conductors, appear between the surfaces and increase impedance. These spaces can be filled by inserting a TIM between the surfaces. As manufacturers make smaller and smaller devices, there is a continuing need for TIMs which are thin and have improved thermal conductivity to efficiently transfer heat from electronic components to thermal management aids.
Composites containing nanotubes randomly distributed in a matrix are known for use as TIMs in the art. However, when nanotubes are oriented in an array instead of being randomly distributed, the array may exhibit improved properties, such as thermal conductivity. It is difficult to produce TIMs containing such arrays.